Retrieving rust from oxidized steel wool

[Gokuson123]

Ok so I have done the steel wool in vinegar, bleach, and water, but all I have is a soupy brown water and some steel wool which is 1/4 surface rust. And everything is soaked in chemicals. How do I remove the rust aside form waiting a month for the water to evaporate?

 

[mrjeffy321]

Take out the steel wool and wait for the Iron Oxide to settle to the bottom of the container. After the Fe2O3 has settled, decant off the clear solution left on top. Then add clean water and repeat the process several times to wash the Fe2O3.
Or you could just filter it.

 

[Gokuson123]

I tried filtering through coffee filters, but it just soaked it all up and now I have 5 wet filters. They didn't want to dry, one did, but the rust embedded itself into the filter so I couldn't remove it.

 

[mrjeffy321]

How much Iron Oxide did you produce? If it is such a small amount that it is all getting soaked up into the filters, you are going to need to consider a much slower form of extraction (possibly evaporation) so as not to loose most of your yeild in the process.

Are the filters doing there job, or is much of the Fe2O3 simply passing through the poors of the coffee filter?
How long do the Fe2O3 particles take to settle to the bottom of the container...more than a few hours?

 

[Gokuson123]

Not many particles settled to the bottom after about 5 hours, and brown water went straight through the filters. I tried electrolysis on a nail, and after one day it did nothing. Having some bad luck here.

 

[radium girl]

I see the last post was nearly three years old, but I am now retracing the steps you describe and having little luck. My son and I made the solution of vinegar and bleach, producing hypochlorous acid, put in the fine steel wool, and let the reaction products settle into a fine silt on the bottom of a jar. We poured off the top solvent, rinsed with distilled H2O and let the reaction products settle again. Then we used a coffee filter to try to trap the rust particles. These were so enmeshed in the filter that we couldn't scrape any off to speak of.

Next we tried evaporation without rinsing with water. A lot of crusty brown scabs formed on the bottom of the jar. Under inspection with a good microscope these turned out to be a mix of a dendritic crystalline product, reddish on the edges but translucent in the body, and what appeared to be small hunks of oxidized steel. The stuff was attracted to a magnet because most of the mass was still steel.

We tried to go ahead and heat this product with an ethanol stove using a spoon as the reaction vessel. The oxidition products turned dark while being heated. Then some of the stuff may have reoxidized while cooling. Microscopic inspection showed that some small boli of pure-looking black material may have formed. But these were few.

My opinion is that this experiment is poorly thought out. It's one of those things that seem to work as long as no one actually does the experiment, like a bad recipe in a poor cookbook. Anyone with any better technique out there?

 

[mrjeffy321]

This reaction absolutely does work.

2 Fe + 3 NaOCl --> Fe2O3 + NaCl

Make sure that you are using enough bleach to fully oxidize all of the steel wool. When it is fully oxidized there will be no little metal fibers from the steel wool left over, it will all turn into a reddish-brown powder which settles to the bottom of the container.

 

[Borek]

Also note that steel wool doesn't equal steel wool, a lot depends on the steel type. Not that I can help much in selection.

 

[mrjeffy321]

That is true, not all steel wools are created equal. Ideally you want just pure iron, in as fine of a particle size as you can get (in order to speed up the reaction), and steel wool just happens to be a convenient approximation this. You do not want any soaps or anti-rust coatings on the steel wool. I used to like using "Rhodes American Steel Wool" for this purpose.

 

[Thorius]

well, just my opinion. The reaction with bleach should produce hydrated iron(III) oxide. Fe(OH)3 or Fe2O3.3H2O. One needs to heat the hydrated oxide to over 200 deg. celsius to get the oxide, which should be red. (hydrate is brown or yellow).

2Fe(s) + 3NaOCl(aq) + 3H2O(l) --> 2 Fe(OH)3(s) + NaCl(aq)

Many documents state that sodium hypochlorite in contact with heavy metals such as nickel, copper, and iron should produce oxygen gas? So it is probably the oxygen released at the surface of iron and water that cause the rusting, or is there some other reaction taking place?

sodium hypochlorite decomposes as following.

2NaOCl --> 2NaCl + O2(g) with contact with heavy metals and in contact with ultraviolet radiation (sunlight).

With vinegar and bleach:

Ch3COOH + NaOCl --> HOCl + NaAc (where sodium acetate may act as an electrolyte)

I'm not sure about the following.

2Fe + 6HOCl --> Fe2O3.3H2O + 3Cl2(g)

or is it.

2Fe + 3HOCl + 3H20 --> Fe2O3.3H20 + 3HCl

P.S. Try 1 part by vol. vinegar to 2 parts by vol. bleach. Do this outside or in a fume hood. Hope this helps.